citadel
About: Citadel is an advanced messaging and collaboration system for groupware and BBS applications (preferred OS: Linux).
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smtp_util.c
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1/*
2 * Utility functions for the Citadel SMTP implementation
3 *
4 * Copyright (c) 1998-2021 by the citadel.org team
5 *
6 * This program is open source software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 3.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 */
14
15#include "sysdep.h"
16#include <stdlib.h>
17#include <unistd.h>
18#include <stdio.h>
19#include <termios.h>
20#include <fcntl.h>
21#include <signal.h>
22#include <pwd.h>
23#include <errno.h>
24#include <sys/types.h>
25#include <syslog.h>
26#include <time.h>
27#include <sys/wait.h>
28#include <ctype.h>
29#include <string.h>
30#include <limits.h>
31#include <sys/socket.h>
32#include <netinet/in.h>
33#include <arpa/inet.h>
34#include <libcitadel.h>
35#include "citadel.h"
36#include "server.h"
37#include "citserver.h"
38#include "support.h"
39#include "config.h"
40#include "control.h"
41#include "user_ops.h"
42#include "database.h"
43#include "msgbase.h"
44#include "internet_addressing.h"
45#include "genstamp.h"
46#include "domain.h"
47#include "clientsocket.h"
48#include "locate_host.h"
49#include "citadel_dirs.h"
50#include "ctdl_module.h"
51#include "smtp_util.h"
52
53const char *smtp_get_Recipients(void) {
54 struct citsmtp *sSMTP = SMTP;
55
56 if (sSMTP == NULL)
57 return NULL;
58 else return ChrPtr(sSMTP->from);
59}
60
61
62/*
63 * smtp_do_bounce() is caled by smtp_process_one_msg() to scan a set of delivery
64 * instructions for errors and produce/deliver a "bounce" message (delivery
65 * status notification).
66 *
67 * is_final should be set to:
68 * SDB_BOUNCE_FATALS Advise the sender of all 5XX (permanent failures)
69 * SDB_BOUNCE_ALL Advise the sender that all deliveries have failed and will not be retried
70 * SDB_WARN Warn the sender about all 4XX transient delays
71 */
72void smtp_do_bounce(const char *instr, int is_final) {
73 int i;
74 int lines;
75 int status;
76 char buf[1024];
77 char key[1024];
78 char addr[1024];
79 char dsn[1024];
80 char bounceto[1024];
81 StrBuf *boundary;
82 int num_bounces = 0;
83 int bounce_this = 0;
84 struct CtdlMessage *bmsg = NULL;
85 struct recptypes *valid;
86 int successful_bounce = 0;
87 static int seq = 0;
88 StrBuf *BounceMB;
89 long omsgid = (-1);
90
91 syslog(LOG_DEBUG, "smtp_do_bounce() called");
92 strcpy(bounceto, "");
93 boundary = NewStrBufPlain(HKEY("=_Citadel_Multipart_"));
94
95 StrBufAppendPrintf(boundary, "%s_%04x%04x", CtdlGetConfigStr("c_fqdn"), getpid(), ++seq);
96
97 /* Start building our bounce message */
98
99 bmsg = (struct CtdlMessage *) malloc(sizeof(struct CtdlMessage));
100 if (bmsg == NULL) return;
101 memset(bmsg, 0, sizeof(struct CtdlMessage));
102 BounceMB = NewStrBufPlain(NULL, 1024);
103
105 bmsg->cm_anon_type = MES_NORMAL;
107 CM_SetField(bmsg, eAuthor, HKEY("Citadel"));
108 CM_SetField(bmsg, eOriginalRoom, HKEY(MAILROOM));
109 CM_SetField(bmsg, eMsgSubject, HKEY("Delivery Status Notification (Failure)"));
110 StrBufAppendBufPlain(BounceMB, HKEY("Content-type: multipart/mixed; boundary=\""), 0);
111 StrBufAppendBuf(BounceMB, boundary, 0);
112 StrBufAppendBufPlain(BounceMB, HKEY("\"\r\n"), 0);
113 StrBufAppendBufPlain(BounceMB, HKEY("MIME-Version: 1.0\r\n"), 0);
114 StrBufAppendBufPlain(BounceMB, HKEY("X-Mailer: " CITADEL "\r\n"), 0);
115 StrBufAppendBufPlain(BounceMB, HKEY("\r\nThis is a multipart message in MIME format.\r\n\r\n"), 0);
116 StrBufAppendBufPlain(BounceMB, HKEY("--"), 0);
117 StrBufAppendBuf(BounceMB, boundary, 0);
118 StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
119 StrBufAppendBufPlain(BounceMB, HKEY("Content-type: text/plain\r\n\r\n"), 0);
120
121 if (is_final == SDB_BOUNCE_ALL) {
122 StrBufAppendBufPlain(
123 BounceMB,
124 HKEY( "A message you sent could not be delivered "
125 "to some or all of its recipients\ndue to "
126 "prolonged unavailability of its destination(s).\n"
127 "Giving up on the following addresses:\n\n"),
128 0);
129 }
130 else if (is_final == SDB_BOUNCE_FATALS) {
131 StrBufAppendBufPlain(
132 BounceMB,
133 HKEY( "A message you sent could not be delivered "
134 "to some or all of its recipients.\n"
135 "The following addresses were undeliverable:\n\n"),
136 0);
137 }
138 else if (is_final == SDB_WARN) {
139 StrBufAppendBufPlain(
140 BounceMB,
141 HKEY("A message you sent has not been delivered "
142 "to some or all of its recipients.\n"
143 "Citadel will continue attempting delivery for five days.\n"
144 "The following addresses were undeliverable:\n\n"),
145 0);
146 }
147 else { // should never get here
148 StrBufAppendBufPlain(BounceMB, HKEY("This message should never occur.\n\n"), 0);
149 }
150
151 /*
152 * Now go through the instructions checking for stuff.
153 */
154 lines = num_tokens(instr, '\n');
155 for (i=0; i<lines; ++i) {
156 long addrlen;
157 long dsnlen;
158 extract_token(buf, instr, i, '\n', sizeof buf);
159 extract_token(key, buf, 0, '|', sizeof key);
160 addrlen = extract_token(addr, buf, 1, '|', sizeof addr);
161 status = extract_int(buf, 2);
162 dsnlen = extract_token(dsn, buf, 3, '|', sizeof dsn);
163 bounce_this = 0;
164
165 syslog(LOG_DEBUG, "key=<%s> addr=<%s> status=%d dsn=<%s>", key, addr, status, dsn);
166
167 if (!strcasecmp(key, "bounceto")) {
168 strcpy(bounceto, addr);
169 }
170
171 if (!strcasecmp(key, "msgid")) {
172 omsgid = atol(addr);
173 }
174
175 if (!strcasecmp(key, "remote")) {
176 if ((is_final == SDB_BOUNCE_FATALS) && (status == 5)) bounce_this = 1;
177 if ((is_final == SDB_BOUNCE_ALL) && (status != 2)) bounce_this = 1;
178 if ((is_final == SDB_WARN) && (status == 4)) bounce_this = 1;
179 }
180
181 if (bounce_this) {
182 ++num_bounces;
183 StrBufAppendBufPlain(BounceMB, addr, addrlen, 0);
184 StrBufAppendBufPlain(BounceMB, HKEY(": "), 0);
185 StrBufAppendBufPlain(BounceMB, dsn, dsnlen, 0);
186 StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
187 }
188 }
189
190 /* Attach the original message */
191 if (omsgid >= 0) {
192 StrBufAppendBufPlain(BounceMB, HKEY("--"), 0);
193 StrBufAppendBuf(BounceMB, boundary, 0);
194 StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
195 StrBufAppendBufPlain(BounceMB, HKEY("Content-type: message/rfc822\r\n"), 0);
196 StrBufAppendBufPlain(BounceMB, HKEY("Content-Transfer-Encoding: 7bit\r\n"), 0);
197 StrBufAppendBufPlain(BounceMB, HKEY("Content-Disposition: inline\r\n"), 0);
198 StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
199
200 CC->redirect_buffer = NewStrBufPlain(NULL, SIZ);
201 CtdlOutputMsg(omsgid,
202 MT_RFC822,
204 0, 1, NULL, 0,
205 NULL, NULL, NULL
206 );
207 StrBufAppendBuf(BounceMB, CC->redirect_buffer, 0);
208 FreeStrBuf(&CC->redirect_buffer);
209 }
210
211 /* Close the multipart MIME scope */
212 StrBufAppendBufPlain(BounceMB, HKEY("--"), 0);
213 StrBufAppendBuf(BounceMB, boundary, 0);
214 StrBufAppendBufPlain(BounceMB, HKEY("--\r\n"), 0);
215 CM_SetAsFieldSB(bmsg, eMesageText, &BounceMB);
216
217 /* Deliver the bounce if there's anything worth mentioning */
218 syslog(LOG_DEBUG, "num_bounces = %d", num_bounces);
219 if (num_bounces > 0) {
220
221 /* First try the user who sent the message */
222 if (IsEmptyStr(bounceto)) {
223 syslog(LOG_ERR, "No bounce address specified");
224 }
225 else {
226 syslog(LOG_DEBUG, "bounce to user <%s>", bounceto);
227 }
228 /* Can we deliver the bounce to the original sender? */
229 valid = validate_recipients(bounceto, smtp_get_Recipients (), 0);
230 if (valid != NULL) {
231 if (valid->num_error == 0) {
232 CtdlSubmitMsg(bmsg, valid, "");
233 successful_bounce = 1;
234 }
235 }
236
237 /* If not, post it in the Aide> room */
238 if (successful_bounce == 0) {
239 CtdlSubmitMsg(bmsg, NULL, CtdlGetConfigStr("c_aideroom"));
240 }
241
242 /* Free up the memory we used */
243 if (valid != NULL) {
244 free_recipients(valid);
245 }
246 }
247 FreeStrBuf(&boundary);
248 CM_Free(bmsg);
249 syslog(LOG_DEBUG, "Done processing bounces");
250}
251
252
253char *smtpcodes[][2] = {
254 { "211 - System status / system help reply" },
255 { "214", "Help message" },
256 { "220", "Domain service ready" },
257 { "221", "Domain service closing transmission channel" },
258 { "250", "Requested mail action completed and OK" },
259 { "251", "Not Local User, forward email to forward path" },
260 { "252", "Cannot Verify user, will attempt delivery later" },
261 { "253", "Pending messages for node started" },
262 { "354", "Start mail input; end with ." },
263 { "355", "Octet-offset is the transaction offset" },
264 { "421", "Domain service not available, closing transmission channel" },
265 { "432", "Domain service not available, closing transmission channel" },
266 { "450", "Requested mail action not taken: mailbox unavailable. request refused" },
267 { "451", "Requested action aborted: local error in processing Request is unable to be processed, try again" },
268 { "452", "Requested action not taken: insufficient system storage" },
269 { "453", "No mail" },
270 { "454", "TLS not available due to temporary reason. Encryption required for requested authentication mechanism" },
271 { "458", "Unable to queue messages for node" },
272 { "459", "Node not allowed: reason" },
273 { "500", "Syntax error, command unrecognized" },
274 { "501", "Syntax error in parameters or arguments" },
275 { "502", "Command not implemented" },
276 { "503", "Bad sequence of commands" },
277 { "504", "Command parameter not implemented" },
278 { "510", "Check the recipient address" },
279 { "512", "Domain can not be found. Unknown host." },
280 { "515", "Destination mailbox address invalid" },
281 { "517", "Problem with senders mail attribute, check properties" },
282 { "521", "Domain does not accept mail" },
283 { "522", "Recipient has exceeded mailbox limit" },
284 { "523", "Server limit exceeded. Message too large" },
285 { "530", "Access Denied. Authentication required" },
286 { "531", "Mail system Full" },
287 { "533", "Remote server has insufficient disk space to hold email" },
288 { "534", "Authentication mechanism is too weak. Message too big" },
289 { "535", "Multiple servers using same IP. Required Authentication" },
290 { "538", "Encryption required for requested authentication mechanism" },
291 { "540", "Email address has no DNS Server" },
292 { "541", "No response from host" },
293 { "542", "Bad Connection" },
294 { "543", "Routing server failure. No available route" },
295 { "546", "Email looping" },
296 { "547", "Delivery time-out" },
297 { "550", "Requested action not taken: mailbox unavailable or relaying denied" },
298 { "551", "User not local; please try forward path" },
299 { "552", "Requested mail action aborted: exceeded storage allocation" },
300 { "553", "Requested action not taken: mailbox name not allowed" },
301 { "554", "Transaction failed" }
302};
303
304
305char *smtpstatus(int code) {
306 int i;
307
308 for (i=0; i<(sizeof(smtpcodes)/sizeof(char *)/2); ++i) {
309 if (atoi(smtpcodes[i][0]) == code) {
310 return(smtpcodes[i][1]);
311 }
312 }
313
314 return("Unknown or other SMTP status");
315}
#define CITADEL
Definition: citadel.h:33
#define MES_NORMAL
Definition: citadel.h:135
char * CtdlGetConfigStr(char *key)
Definition: config.c:384
#define CC
Definition: context.h:140
struct recptypes * validate_recipients(char *supplied_recipients, const char *RemoteIdentifier, int Flags)
void free_recipients(struct recptypes *valid)
void CM_Free(struct CtdlMessage *msg)
Definition: msgbase.c:310
int CtdlOutputMsg(long msg_num, int mode, int headers_only, int do_proto, int crlf, char *section, int flags, char **Author, char **Address, char **MessageID)
Definition: msgbase.c:1481
long CtdlSubmitMsg(struct CtdlMessage *msg, struct recptypes *recps, const char *force)
Definition: msgbase.c:2603
void CM_SetField(struct CtdlMessage *Msg, eMsgField which, const char *buf, long length)
Definition: msgbase.c:142
void CM_SetAsFieldSB(struct CtdlMessage *Msg, eMsgField which, StrBuf **buf)
Definition: msgbase.c:258
#define HEADERS_ALL
Definition: msgbase.h:39
void * malloc(size_t)
#define CTDLMESSAGE_MAGIC
Definition: server.h:42
@ eMesageText
Definition: server.h:315
@ eAuthor
Definition: server.h:307
@ eMsgSubject
Definition: server.h:320
@ eOriginalRoom
Definition: server.h:316
#define FMT_RFC822
Definition: server.h:178
@ MT_RFC822
Definition: server.h:167
const char * smtp_get_Recipients(void)
Definition: smtp_util.c:53
char * smtpcodes[][2]
Definition: smtp_util.c:253
char * smtpstatus(int code)
Definition: smtp_util.c:305
void smtp_do_bounce(const char *instr, int is_final)
Definition: smtp_util.c:72
@ SDB_BOUNCE_FATALS
Definition: smtp_util.h:37
@ SDB_BOUNCE_ALL
Definition: smtp_util.h:38
@ SDB_WARN
Definition: smtp_util.h:39
#define SMTP
Definition: smtp_util.h:33
int cm_magic
Definition: server.h:34
char cm_anon_type
Definition: server.h:35
char cm_format_type
Definition: server.h:36
StrBuf * from
Definition: smtp_util.h:20
int num_error
Definition: server.h:53
#define MAILROOM
Definition: sysconfig.h:61
#define SIZ
Definition: sysconfig.h:33